Grate and grate bar



March 10, 1936. M. A. HOFFT 2,033,576

GRATE AND GRATE BAR' Filed Dec. 22, 1934 2 Sheets-Sheet l INVENTOR Ma zzricefl H offt B ATTORNEYS March 10, 1936. AIIHOFFT J I 2,033,576

GRATE AND GRATE BAR Filed Dec. 22, 1954 2 Sheets-Sheet 2 INVENTOR Maurice H. Ho/ft,

ATTORNEYS Patented Mar. 10, 1936 UNITED STATES;

PATENT OFFICE 4 Claims.

My invention relates to improvements in furnace grates and particularly to that type of grate used in furnaces for burning such fuels as bagasse, garbage, refuse and other fuels.

In this type of furnace the grate preferably is inclined at an angle from front to rear and comprises a plurality of grate bars having arranged in spaces between the bars pushers which from time to time are rocked on their pivots for the purpose of causing the material on the grate to be moved forward. Heretofore in this particular type of grate it has been diificult to move the fuel forward due to the fact that the pushers could. not be rocked sufficiently on their pivots to give sufficient forward impetus to the fuel.

It is one of the present objects of my invention to provide a grate bar wherein the pushers are so arranged that a greater throw may be imparted thereto.

For the purpose of disclosing my invention I have illustrated an embodiment thereof in the accompanying drawings. I

Fig. 1 is a longitudinal sectional view, more or less diagrammatic, of a furnace embodying my invention; 7

Fig. 2 is a perspective view of a portion of a grate embodying my invention, and

Fig. 3 is a detailed elevation, partly in section, showing more particularly the pushers.

In the embodiment of the invention the furnace I has the usual front wall or face plate 2. The grate 3 is arranged within the furnace at any suitable desired angle, the angle preferably being greater than twelve degrees and not exceeding 37 degrees, although this is not arbitrary as the angle is varied in accordance with the character of .the fuel to be burned.

One end of the grate is adapted to rest on the cross beam 4 at the front end and the other end of the grate is adapted to rest on the bearing plate 5 at its rear end. The grate may dump into an ashpit 6 in which may be arranged suitable rotary clinker grinders l and the ground clinkers drop from the grinders into the bottom of the ashpit, or are otherwise disposed of.

The grate is preferably formed of a series of grate bars which are formed preferably of two sections. The rear or bottom section has a foot plate 9 adapted to rest on the bearing plate 5, which foot plate is carried at the lower end of a comparatively deep narrow rib or plate It), the upper edge of which carries along its sides a series of spaced teeth I I. At suitable intervals along the upper edge of the rib l0 rearwardly and downwardly inclined notches l2 are formed,

which notches form pockets for the trunnions of the pushers to be hereinafter described. Imme-- I diately in front of the trunnion pockets I2, I provide wider teeth as at 13, which are braced at their outer edges by ribs M. The advantages of these wider teeth or spacers will appear more fully hereinafter. While I have shown these spacers as teeth they may take other forms than that illustrated.

The forward end of the grate in the structure illustrated comprises a pair of side bars l5 connected together by cross bars [6, although they may take other desired forms, to provide air spaces l's' therebetween. One of these forward grate bars dovetails as at 8 with the forward end of the rearmost grate bar to form in effect a continuous bar, and if desired may be formed integral with the rear bar. The grate bars thus formed are arranged side by side as shown in Fig. 2 and in this arrangement spaces are pro vided of considerable width to receive pivotedv pushers [9 which are provided at their lower ends with oppositely-projecting trunnions 2E! seating in i the trunnion-receiving slots H2 in the grate bars. The main body of each pusher comprises parallel side plates 2| substantially triangular in elevation and these side plates are connected. at their upper edges by transverse grate bars 22, which are spaced'apart to form air passages, and at their ends these plates are connected by arc-shaped plates 23 which form closures for the space between the rear ends of the plates so that when the pushers are thrown upwardly and forwardly as shown in Fig. 2, that portion of the fuel bed lying behind the plates will be prevented from falling through the grate as well as from moving rearwardly on the grate.

The side bars are continued rearward as at 24 to form operating arms and each series of pushers is preferably connected by cross rods 25 fitting in notched recesses 26 in the ends of the arms. To additionally strengthen the arms 24 and. form a rigid connection therebetween I can provide angle plates, as 21. Each of the rods 25 is connected with an operating arm 28 which pref erably, at its connecting end is hook-shaped as at 29 to provide clearance, although in some instances this is not essential.

It will be noted that the distances between the centers of the pushers, as between the center 30 of the rearmost pusher and 30a of the next adjacent pusher, is considerably greater than the length of the pusher. Due to this spacing between the centers of the trunnion notches I am enabled to provide a spacing which will permit clearance between the operating arms. of the successive pushers so that, with, for ins'thnce, the two foremost pushers in their retracted positions, the rearmost arm can be rocked to a position to pass the pusher into substantially vertical position, or even to an extent to tilt the face of the pusher forward. At the same time, with this spacing of the centers the space between the pushers is filled in by the teeth or spacers l3 on the grate bar so that there is never any danger of the fuel dropping through the gate.

Heretofore it has never been practical to sufficiently space the centers of the pushers to permit their operating arms to clear and as a result a satisfactory feeding forward of the fuel has not been accomplished. In other words, the pushers have not really acted as pushers but merely as agitators. By increasing the throw of the pushers by my above improvement I am enabled more definitely and positively to feed the fuel towards the rear of the grate and actually push the fuel forward.

I claim as my invention:

1. In a furnace, the combination of a plural-- ity of grate bars each formed of a comparatively deep vertical rib having a plurality of laterallyprojecting teeth adjacent its upper edge and a plurality of transverse notches in its upper edge to receive pusher trunnions, and a plurality of pushers mounted in the space between said bars and having trunnions received in said trunnion notches, the distance between the trunnion notches in each bar being sufficiently greater than the face length of the pushers to provide a clearance between the pushers from front to back, and the laterally-projecting teeth on the rib adjacent said trunnion notches being longer than the remaining laterally-projecting teeth on the rib to fill the space between the pushers.

2. In a furnace, the combination of a plurality of grate bars each formed of a comparatively deep vertical rib having a plurality of laterallyprojecting teeth adjacent its upper edge and a plurality of notches in its upper edge to receive pusher trunnions, a plurality of pushers mounted in the spaces between said bars and having trunnions received in said trunnion notches and downwardly-projecting operating arms projecting below the grate, the distance between the centers of the trunion notches in the bars for each pusher and the next succeeding pusher being greater than the face length of the pushers and the radial distance between the center of the pusher trunnion and the end of its operating arm to provide a clearance between the succeeding pushers, the laterally-projecting teeth on the rib adjacent the trunnion notches being longer than the remaining teeth on the rib to fill the space between the pushers.

3. In a furnace, the combination of a plurality of grate bars each formed of a comparatively deep vertical rib having a plurality of laterallyprojecting teeth adjacent its upper edge and a plurality of transverse notches in its upper edge to receive pusher trunnions and a plurality of pushers mounted in the space between said bars and having trunnions received in said trunnion notches, the distance between the trunnion notches in each bar being sufliciently greater than the face length of the pushers to provide a clearance between the pushers from front to back of the bar, and laterally-projecting filler members on the rib adjacent said trunnion notches and projecting a greater distance than the laterally-projecting teeth on the rib to fill the spaces between the pushers.

4. As a new article of manufacture, a furnace grate bar comprising a comparatively deep vertical rib having a plurality of laterally-projecting teeth adjacent its upper edge and a plurality of trunnion-receiving openings therein, and laterally-projecting filler members adjacent the upper edge of said rib of greater lateral extent than said teeth and positioned adjacent said openings. 40

MAURICE A. HOFF'I. 

